1、 Disease manifestation

Grey leaf spot usually only affects the leaves of tomatoes. In the early stage of the disease, its leaf surface will have dark circular spots, and will expand around along the leaf veins, and the shape is usually irregular. Then the middle part of the leaf will fade, turn gray white or grayish brown, and the disease spot will sag and become thinner at the same time. Finally, the leaves will break and pierce, and fall off in severe cases

2、 Cause of disease

Tomato gray leaf spot is a disease caused by fungi. Failure to do a good job in disinfection in winter leads to bacteria remaining on the seeds. When the temperature and humidity are suitable for its growth in the second year, it will start to infect the plants. In addition, it can also spread through wind and rain and expand the area of infection. If the plant grows weak, it is more likely to suffer from such diseases

3、 Treatment method

After the plant is found to be sick, the diseased leaves need to be cut off immediately and buried or burned intensively, so as to completely eliminate the bacteria and eliminate the possibility of recurrence. After that, use carbendazim or chlorothalonil and other drugs to spray on the plant. The spraying position should be comprehensive. Although it only infects the leaves, there will be residues on the stems or branches

4、 How to prevent

In order to prevent tomato gray leaf spot, we should first select seeds and generally select varieties with strong disease resistance, which can reduce the possibility of disease. Secondly, we should strengthen daily management and timely apply phosphorus and potassium fertilizer to improve the disease resistance of plants. In addition, it is also necessary to do a good job in dehumidification during the period of easy disease and strengthen environmental ventilation to avoid the breeding of bacteria